Golombek D A, Escolar E, Burin L J, De Brito Sánchez M G, Cardinali D P
Departamento de Fisiologia, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Eur J Pharmacol. 1991 Feb 26;194(1):25-30. doi: 10.1016/0014-2999(91)90119-b.
The aim of this study was to determine whether melatonin-induced analgesia in mice exhibits the time dependency known to occur for several other effects of the hormone, and to analyze to what extent the activity of melatonin can be inhibited by the opiate antagonist naloxone or the central-type benzodiazepine (BZP) antagonist Ro 15-1788. Analgesia was assessed with the hot plate procedure. There was a significant diurnal variation in the pain threshold, with an increase in latency during the dark phase of the daily photo period. Melatonin (20-40 mg/kg i.p.) exhibited maximal analgesic effects at late evening (20:00 h). The administration of naloxone or Ro 15-1788 at 20:00 h, although unable by themselves to modify pain threshold, blunted the analgesic response to melatonin. Significant increases in the latency of the hot plate response were found after diazepam injection, an effect blocked by Ro 15-1788 or naloxone. These results indicate that time-dependent melatonin analgesia is sensitive to opioid or central-type BZP antagonism.
本研究的目的是确定褪黑素诱导的小鼠镇痛作用是否表现出该激素其他几种作用所具有的时间依赖性，并分析阿片拮抗剂纳洛酮或中枢型苯二氮䓬（BZP）拮抗剂Ro 15-1788能在多大程度上抑制褪黑素的活性。采用热板法评估镇痛效果。疼痛阈值存在显著的昼夜变化，在每日光照周期的黑暗阶段潜伏期增加。褪黑素（20 - 40毫克/千克腹腔注射）在傍晚（20:00）表现出最大镇痛效果。在20:00给予纳洛酮或Ro 15-1788，虽然它们自身不能改变疼痛阈值，但却减弱了对褪黑素的镇痛反应。注射地西泮后，热板反应潜伏期显著增加，这一效应被Ro 15-1788或纳洛酮阻断。这些结果表明，时间依赖性的褪黑素镇痛作用对阿片类或中枢型BZP拮抗作用敏感。
